Magnetic brush development apparatus for applying developer material to a latent image in an electrostatographic reproduction apparatus are well known in the art. Such apparatus may include a housing having a sump portion which contains a mixture of carrier particles and pigmented marking particles. The material in the sump is agitated to triboelectrically charge the material prior to delivering it to a magnetic brush where it can be brought into association with, and electrostatically transferred to, an electrostatic latent image to develop such image.
Copending, commonly assigned U.S. Pat. application Ser. No. 289,147, filed Dec. 23, 1988, in the name of B. J. Joseph discloses a ribbon blender that is used for agitating (mixing), feeding and triboelectrically charging developer material in the sump portion of a magnetic brush development apparatus, and a feed mechanism that delivers material from the sump portion to a magnetic brush under the control of a metering assembly that includes a closeable slot between the sump and the magnetic brush. Although the metering assembly disclosed by Joseph has been found to operate satisfactorily, toner clogging at the slot can be further reduced by the metering assembly of the present invention.